#include "main/utils.h"
using namespace std;

class Solution {
  public:
    int singleNumber(vector<int>& nums) {
      int ret = 0;
      for (auto n : nums) {
        ret ^= n;
      }
      return ret;
    }
};

int main() {
  vector<int> input = {2, 2, 1};
  Solution su;
  cout << su.singleNumber(input) << endl;
}
